The high-pressure pump is generally provided with a plunger which reciprocates along a camshaft of an engine. Specifically, when the plunger slides down from its top dead center to its bottom dead center, a fuel in a fuel gallery is suctioned into a pressurization chamber (suction stroke). When the plunger slides up from the bottom dead center to the top dead center, a part of the low-pressure fuel is returned to the fuel gallery from the pressurization chamber (metering stroke). Then, after a metering valve is closed, when the plunger further slides up, the fuel in the pressurization chamber is pressurized by the plunger (pressurization stroke).
During the metering stroke, the metering valve is lifted up. If dynamic pressure of fuel returning from the pressurization chamber to the fuel gallery is allied to the lifted metering valve, the valve is brought into a closed position by itself. This phenomenon is referred to as self-closing phenomenon. The dynamic pressure corresponds to kinetic energy per unit volume of the fluid.
Japanese Patent No. 3833505 shows a metering valve having a cup-shaped valve body in which a spring is provided. A stopper defines a fuel passage and a sliding surface on which valve body slides. In order to avoid wringing, fuel is introduced inside of the valve body. The dynamic pressure of fuel discharged during the metering stroke is applied to an inside surface of the valve body, which may cause the self-closing phenomenon.
Japanese Patent No. 2762652 and Japanese Patent No. 4285883 show a valve having a fuel passage radially outside of a contacting surface between the valve and the stopper. Specifically, in Japanese Patent No. 2762652, a stopper is provided with a penetrating hole, whereby it is restricted that the dynamic pressure of fuel is applied to a tip surface of the valve. In Japanese Patent No. 4285883, a stopper plate has a notch portion, whereby it is restricted that the dynamic pressure of fuel is applied to a tip surface of the valve.
In Japanese Patent No. 2762652, since the tip surface of the valve defines a valve lift amount, the tip surface is polished. Thus, an outer periphery of the tip surface is tapered. Also in Japanese Patent No. 4285883, an outer periphery of the valve is tapered.
As above, in the conventional valve, although the dynamic pressure of fuel is not applied to a tip surface of the valve, the dynamic pressure of fuel is applied to the tapered surface, which may cause a self-closing phenomenon.